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BTS
04-01-2013, 04:14 PM
Really, is there any discernible difference or are they much the same?

Both claim to be produced to be the most efficient shaped and size for absorbing CO2

The only difference I see is

797: 1 - 2.5mm triangular shaped

812: 2mm cylindrical

What am I missing or is this another case of gumf and either will do the job as well as each other....

WFO
07-01-2013, 09:35 AM
One should give better WOB, the other more time until breakthrough. Believe the common one is the fine stuff.

Just to be pedantic about the names, and I may be wrong, I thought that the 797 was an 8 - 12 mesh size and the bigger cylindrical type was known as CD, 4-8 mesh size maybe.


I think the intersorb 812 and is the similar sizes as the sofnoline 797.

BTS
07-01-2013, 09:51 AM
One should give better WOB, the other more time until breakthrough. Believe the common one is the fine stuff.


Thanks for replying but that doesn't really clear anything up, which does what?

JPTaylor
07-01-2013, 10:10 AM
Why don't you call the nice people at AP & ask them! They'll say use the stuff it was designed for & tested on i.e. the 797 Sofnolime.

It's easy enough to get hold of in this country, I'd stick to that.

Seem to remember one guy killing himself using some cheap medical lime he had access to thru his work.....

BTS
07-01-2013, 12:04 PM
Why don't you call the nice people at AP & ask them! They'll say use the stuff it was designed for & tested on i.e. the 797 Sofnolime.

It's easy enough to get hold of in this country, I'd stick to that.

Seem to remember one guy killing himself using some cheap medical lime he had access to thru his work.....

Because I want to know is there an actual differece or is it the usual industry smoke and mirrors. Large partical medical lime is fine in a cascade system with a man and a load of machines that go ping but I know not to use that in a RB, the difference between these is minimal, more to do with shape. Have AP tested the units with 812?

This isn't a case of asking to save a few quid, it is asking to understand the difference.

If you don't know, that is fine, maybe someone can enlighten us all...

gordyp
07-01-2013, 12:28 PM
I don't know the answer, however it appears that Revo have approved it and they will have tested it in their machine.

Carbon dioxide scrubber products for rebreather diving, technical diving and CCR diving - DIVELIME news (http://www.divelime.com/dl_news.html#revo0211)

I'm sure there was an article on the revo website regarding this but I can't now find it. Might be worth e-mailing Paul, I'm sure he'd give you a proper answer.

nickb
07-01-2013, 12:29 PM
AIUI, the only manufacturer to have approved Intersorb 812 is rEvo and then with certain minor caveats.

I've been using it in my JJ for more than a year and have had no issues whatsoever. The fact that it's £60 delivered from DiveLime (http://www.divelime.com/dl_order.html) wasn't my only guiding factor, but it helped ;)

JPTaylor
07-01-2013, 12:33 PM
I don't know the answer, however it appears that Revo have approved it and they will have tested it in their machine.

Carbon dioxide scrubber products for rebreather diving, technical diving and CCR diving - DIVELIME news (http://www.divelime.com/dl_news.html#revo0211)

I'm sure there was an article on the revo website regarding this but I can't now find it. Might be worth e-mailing Paul, I'm sure he'd give you a proper answer.


But I believe BTS dives an Inspiration.....

gordyp
07-01-2013, 12:37 PM
But I believe BTS dives an Inspiration.....

In which case he should fill it with old compost and woodchip cat litter! It'll be fine

JPTaylor
07-01-2013, 12:38 PM
Have AP tested the units with 812?

They've not published any figures except for the standard Sofnolime, if they've tested internally they're unlikely release figures.

WFO
07-01-2013, 03:40 PM
Thanks for replying but that doesn't really clear anything up, which does what?

Between the two different grades of sofnolime (which I thought you were asking about), the bigger stuff gives a better WOB (bigger paths between granules), the smaller stuff gives more duration (more surface area exposed).
In practice the AP units are meant to use fine lime as they've got a decent aspect ratio scrubber to get good WOB out of the smaller stuff.


But if you're asking about sofnolime 797 versus intersorb 812 then the difference is minimal but some tests have shown slight reduction in capacity in very cold water.

Simon TW
07-01-2013, 03:55 PM
The rEvo testing resulted in no difference in performance in warm water + 15deg C

When you're diving in water colder than 15 then reduce the scrubber time from 3 Hours to 2.5. This is for rEvo on both scrubbers but I would think that your unit would be similar.

On your own head be it though.

http://www.revo-rebreathers.com/uploads/intersorb812.pdf

Major Clanger
05-03-2013, 09:01 AM
Bit late to the thread. In real terms I doubt there's much discernible difference between the two sizes used within the three hour window. I don't worry about it for my machine. Re Sofnalime and Intersorb, they may have a similar performance but in my experience the intersorb is a lot dustier and leaves a fine coating in the can and filters, even after trying to reduce this as much as possible during the filling process.

nickb
05-03-2013, 09:18 AM
... in my experience the intersorb is a lot dustier and leaves a fine coating in the can and filters, even after trying to reduce this as much as possible during the filling process.How long ago was this experience? I've been using it for a couple of years now along with Sofnolime and I see no difference.

Major Clanger
05-03-2013, 09:35 AM
How long ago was this experience? I've been using it for a couple of years now along with Sofnolime and I see no difference.

Have been using it in the uk for about 5 months and at the centre in canaries for recent course. On a slighty breezy day try pouring some from about two feet above a jug and you can see the dust. That's my experience anyway from different batches. Still using it. Just needs extra cleaning. My can is clear so shows up easily. Just mindful of the potential to inhale dust.

Baron015
05-03-2013, 09:40 AM
AIUI, the only manufacturer to have approved Intersorb 812 is rEvo and then with certain minor caveats.

I've been using it in my JJ for more than a year and have had no issues whatsoever. The fact that it's £60 delivered from DiveLime (http://www.divelime.com/dl_order.html) wasn't my only guiding factor, but it helped ;)

Having observed Nick is still alive despite using Intersorb 812 from Divelime, I have been using it myself in my JJ since last summer. Also no issues to report.

TB.

nickb
05-03-2013, 09:41 AM
Just mindful of the potential to inhale dust.Isn't that what scrims are for? Seriously, I've had no dust at all downstream of the scrubber, not even on the head. It would have to go some to get right around the loop.

You could always do the Gina G hoover fill technique ;)

notdeadyet
05-03-2013, 10:08 AM
I've found Intersorb was very dusty when I started using it, bad enough that you wouldn't want to fill indoors. I bought a load last year which I'm reaching the end of and it's fine. I wonder if transport plays apart as I've had Sofnolime batches that have been extremely dusty too. I noticed it particularly when I used to buy it from Divex so maybe the 400 miles or so ratlled round a courier van is the cause?

I like Intersorb, very good service from them.

Major Clanger
05-03-2013, 10:38 AM
Having observed Nick is still alive despite using Intersorb 812 from Divelime, I have been using it myself in my JJ since last summer. Also no issues to report.

TB.

In spite of using intersorb I too am still alive, so will carry on using it, dust n all :) NDY may be on to something with effects of transport but in about 10 kegs of sofnalime, I never had dust problems with lime delivered. Maybe that's why it's 10 quid more. Just an observation, that is all ;)

matt
05-03-2013, 11:49 AM
What am I missing or is this another case of gumf and either will do the job as well as each other....

Probably get my head bitten off but anyhow...

Why would you not use 797 (the stuff tested and approved by the manufacturer) in an Inspiration if there is the choice to do so?

I've used CD grade - and in warm water that is fine, but it's a bit like packing marbles.

I would use 812 given the reports but it is not tested by APD so I'd ask there advice before doing so.

I'd also use Grace 4-8 or better the 6-12; but only if I could not get 797. I'd get some data from the factory before doing so.

Matt.

dwhitlow
05-03-2013, 11:59 AM
As Matt says, 797 is tested by AP and recommended and reliably does the job. For the sake of a couple of quid per dive I can't the point.

If we were debating cells...

BTS
05-03-2013, 12:46 PM
Why would you not use 797 (the stuff tested and approved by the manufacturer) in an Inspiration if there is the choice to do so?



Dunno, why do I use a GG BOV instead of the AP one, why have I ditched the yellow box for a steel frame, the tekwing for a frog.. Sometimes there are better alteratives, sometimes companies test with one thing but dont test with another, saying it isn't approved doesn't mean it wouldn't work as well if not better.

It is good to question and look at alternatives, non of us got into diving because we follow the crowd, we got there following our own path.

BTS
05-03-2013, 12:49 PM
If we were debating cells...

Very fair point, the approved cells are no match for the others by many accounts...

matt
05-03-2013, 01:17 PM
Dunno, why do I use a GG BOV instead of the AP one, why have I ditched the yellow box for a steel frame, the tekwing for a frog.. Sometimes there are better alteratives, sometimes companies test with one thing but dont test with another, saying it isn't approved doesn't mean it wouldn't work as well if not better.

Personally I wouldn't as I am unable to measure "better" in any sort of meaningful way. But each to their own - I have no issue with anyone doing what they want and what pleases them.

Matt.

nickb
05-03-2013, 01:20 PM
Personally I wouldn't as I am unable to measure "better" in any sort of meaningful way.If it's cheaper, but the same in all other respects, it must be better.

matt
05-03-2013, 01:26 PM
If it's cheaper, but the same in all other respects, it must be better.

Better things are usually more expensive, or come in a nicer box, or with a better label. Divelime £60 delivered is a good price, mind. Could save myself £75 quid a year...that and the £35 quid saved using £1 Sony batteries and I'm looking at being up by 22 bottles of Ripasso (they are on offer at Tesco at the moment - £5 rather than £8).

Matt.

flyingfisheye
23-03-2015, 08:11 AM
I have used Dive Lime for several years now and find it fine. £60 for 20kg delivered. Was in Sri lanka last year and the only choice you had was Intersorb had the coloured indicator type there, it worked just fine for all of us diving the Hermes. Diving a Sentinel that does have one of the best axial scrubber designs might help I guess.

BTS
23-03-2015, 08:30 AM
Better things are usually more expensive,


This is the great retail con, people believe it, retailers make more profit.

There is an old retail trick, same product, three prices, most people will go for the middle price, the low cost version must be lacking in some way, the top end probably doesn't have enough extra value to warrant the extra cost so the middle one must be the best value for money...

matt
23-03-2015, 09:11 AM
This is the great retail con, people believe it, retailers make more profit.

We're talking about £7.50 difference for 20kg, delivered, (94p per fill), lol.

I agree your principle with wine, though. I'd always buy a £10 bottle over a £20 as I cannot tell the difference. I always buy a case of the £10 - last time with discounts it came to £6 per bottle. Better to concentrate on savings on wine, than on lime!

Matt.

BTS
23-03-2015, 10:19 AM
We're talking about £7.50 difference for 20kg, delivered, (94p per fill), lol.


???? £60 delivered from dive lime or £78.50 plus postage from AP

Look after the pennies, as my gran used to say, and the pounds will look after themselves, or, as I say, less spent on lime more spent on steak and beer...

matt
23-03-2015, 10:36 AM
???? £60 delivered from dive lime or £78.50 plus postage from AP

Look after the pennies, as my gran used to say, and the pounds will look after themselves, or, as I say, less spent on lime more spent on steak and beer...

Before Scuba+Outdoor closed I was getting 797 for £57.50 a tub. I cannot recall how much I paid at Stoney Cove - but it was convenient to pick up 4 tubs there. Custom Divers is £67.50, delivered. It is £75 delivered at GoDive.

£95.30 delivered at AP, think I'll avoid that one!

Matt.

notdeadyet
23-03-2015, 10:46 AM
Other than the dust I've not really seen any reason not to use Intersorb. I've got decent filters in the scrubber so never seen any dust in the loop. 60 quid any reliable dispatch and delivery times which is more than can be said for a lot of shops. Four years and not had a sniff of a problem even in winter.

That said, current keg is MP but that was me leaving it to the last minute and having to go to an actual real physical shop and talk to a proper sentient human. Though not sure some of the staff in Dive Life qualified but at least they had lime.

Vanny
23-03-2015, 04:12 PM
Before Scuba+Outdoor closed I was getting 797 for £57.50 a tub. I cannot recall how much I paid at Stoney Cove - but it was convenient to pick up 4 tubs there. Custom Divers is £67.50, delivered. It is £75 delivered at GoDive.

£95.30 delivered at AP, think I'll avoid that one!



Matt.


67.50 at custom divers plus 9.50 postage

matt
23-03-2015, 05:28 PM
67.50 at custom divers plus 9.50 postage

Humm, I went all the way to the paynow screen and delivery was free...just tried it again and you are right, cheaper to collect at Stoney.

Still wouldn't use the other stuff unless 797 was unavailable.

Matt.

Janos
23-03-2015, 09:05 PM
67.50 at custom divers plus 9.50 postage

Who are about 20 minutes from my house and do a discount if you buy six or more tubs. :)

Janos

Janos
23-03-2015, 09:06 PM
Look after the pennies, as my gran used to say, and the pounds will look after themselves, or, as I say, less spent on lime more spent on steak and beer...

Whereas a mate of mine says: "Focus on the big things. Get a good deal on your mortgage and you don't have to worry about the pennies..."

J

BTS
23-03-2015, 09:37 PM
Who are about 20 minutes from my house and do a discount if you buy six or more tubs. :)

Janos

I thought the JJ recommendation was for 812?


Oh, and we have a really good mortgage... and no other debt...

Janos
23-03-2015, 09:47 PM
I thought the JJ recommendation was for 812?
Oh, and we have a really good mortgage... and no other debt...

I think JJ recommend 797. Please don't make me look through the CE testing to see what they used. My name's not Brad unless I'm going tot he Rocky Horror :)

Good news on the mortgage front. I'm guessing that's worth more pints and steaks than the saving from sofnalime.

Janos

BTS
23-03-2015, 09:52 PM
I think JJ recommend 797.

You mean you are using a lime that may or may not be recommended by the manufacturer!!!!! How are you net dead already????? :OMG:

Janos
23-03-2015, 09:56 PM
You mean you are using a lime that may or may not be recommended by the manufacturer!!!!! How are you net dead already????? :OMG:

It's what my instructor taught me to use.

But don't worry; the paperwork's in order too (page 9, http://jj-ccr.com/media/30609/analog_ce_v.1.00_rev_04_eng_.pdf )

Janos

witchieblackcat
23-03-2015, 11:02 PM
Dunno, why do I use a GG BOV instead of the AP one, why have I ditched the yellow box for a steel frame, the tekwing for a frog.. Sometimes there are better alteratives, sometimes companies test with one thing but dont test with another, saying it isn't approved doesn't mean it wouldn't work as well if not better.

It is good to question and look at alternatives, non of us got into diving because we follow the crowd, we got there following our own path.

You might have a better unit now. Or you might have the equivalent of a 19 year olds souped up Ford Escort with a baked bean can on the exhaust and a ridiculous wing which makes loads of noise on the bypass but is outperformed by a modern 1.0 Corsa.

As long as you're happy though

Steve C
23-03-2017, 07:33 AM
Hope it is ok to resurrect this thread ... any more thoughts / experience in using Intersorb 812 .. particularly in an Inspiration.

I would use Sofnalime if it was not a pain to get hold of in Spain (no local dealer /importer that I can find) and there is a local supplier of the Intersorb.

Cheers

fibre
23-03-2017, 08:48 AM
Hope it is ok to resurrect this thread ... any more thoughts / experience in using Intersorb 812 .. particularly in an Inspiration.

I would use Sofnalime if it was not a pain to get hold of in Spain (no local dealer /importer that I can find) and there is a local supplier of the Intersorb.

Cheers

I use 812 almost exclusively in the UK and used 797 outside of the UK.

I don't think that the dust issue is a problem for me and I didn't really see a difference in WOB between the two.

I am aware that there is potentially a difference in the amount of CO2 that 812 can absorb being lower than 797, but I never push my scrubber.

I read a comment on another forum that said he believed the difference in time available on 797 made up for the difference in price, but you would then need to run a CO2 monitor and push things - something I'm not prepared to do.

Vanny
23-03-2017, 08:53 AM
http://www.xray-mag.com/content/rebreather-sorb-research-unveiled

Not sure if that's any help but interesting

matt
23-03-2017, 02:13 PM
Hope it is ok to resurrect this thread ... any more thoughts / experience in using Intersorb 812 .. particularly in an Inspiration.

I would use Sofnalime if it was not a pain to get hold of in Spain (no local dealer /importer that I can find) and there is a local supplier of the Intersorb.

Cheers

APD say it is not adequately tested in their units, note it doesn't say it's no good.



The problem is no one is dipping their hand in their pocket to pay for all the testing required on the different materials. The tests are time consuming and costly and above all, it has to make business sense… and from our past experience with Sodalime 812 – we didn’t know the limitations of the material until we had a large batch in.[/FONT]

The Intersorb 812 wasn’t the same as 797 as claimed by an Intersorb representative. We learned within 4 test dives, 2 days of testing, that the Tempstik needs adjusting for that material as the warnings are inappropriate and the Intersorb 812s performance wasn’t as good at depth. To properly verify the material in each rebreather will be too costly.

I believe subsequent posts focused on consistency of the product. From my experience warm water negates most evils with absorbent.

Intersurgical say their absorbent is better: http://www.divelong.com/files/test-data1.pdf

Molecular say their absorbent is better: https://jmldiving.com/data/include/cms/Performance_testing_of_Sofnolime_at_depth-October2012.pdf

Look at the test characteristics of each and make your own decision, the test environment is not the same for each.

Cheers
Matt.

Mark Chase
25-03-2017, 10:59 AM
I have used 812 for up to five hours total in a JJ CCR and down to 96m. I have regularly dived it for 3-4 hours single dive depths 60-80m

If I were pushing the max duration (which for me would be over 6 hours on one dive or multiple dives, or over 100m depth) I'd want the 797

For anything else 812 has been fine

I did dive 812 in an Inspo classic but only one tub, so not a great deal of data, but several dives in the 70m zone for over 3 hours

Personaly I think its more dusty but not by enough to make me not use it.

simon mitchell
26-03-2017, 08:22 PM
Hello,

In the course of the spherasorb vs sofnolime study.....

http://bit.do/sorb

.... we ran a couple of 812 canisters. We may finish enough runs to publish a proper comparison, but (based on limited date) there was effectively little difference in duration to significant CO2 break through on our 6 MET protocol between 812 and 797.

The significant difference between spherasorb and 797 has been discussed previously and is documented in the paper which can be accessed at the above link.

Simon M

Martin Parker
27-03-2017, 11:46 AM
Hello,

In the course of the spherasorb vs sofnolime study.....

http://bit.do/sorb

.... we ran a couple of 812 canisters. We may finish enough runs to publish a proper comparison, but (based on limited date) there was effectively little difference in duration to significant CO2 break through on our 6 MET protocol between 812 and 797.

The significant difference between spherasorb and 797 has been discussed previously and is documented in the paper which can be accessed at the above link.

Simon M

Hi Simon,

I think it is appropriate to re-mention that your testing was only done at the surface.

The tests commissioned by Molecular Products compared performance at 40m and in 4C ( CE test rate of 40 RMV and 1.6 lpm CO2) - and it showed the performance of the Intersorb product was down on the Sofnolime 797. From memory it was about 20% down.

Most importantly though, the temp-stik warnings didn't work properly with the Intersorb, and it is the use of the Tempstik that allows worry free, multi-dive, extended use, basically taking the guess work out, giving you lots of extra duration in most diving scenarios.

Martin

Simon TW
20-06-2017, 03:48 PM
Bit old this thread but hey I've been busy.

We took Insersurgical Dive Lime to Sudan for an Expedition. That means that we shipped it in September to Italy and it was then stuffed (yep that's the word that they use and charge you for) into a container for Sudan for use the following April/May it was used on 26 sub 100 metre dives down to a maximum of 213 meters and after a 7 hour run time there was still an hour remaining on the rEvo top scrubber.


Should add that me had no issues.

jamesp
20-06-2017, 03:54 PM
Bit old this thread but hey I've been busy.

We took Insersurgical Dive Lime to Sudan for an Expedition. That means that we shipped it in September to Italy and it was then stuffed (yep that's the word that they use and charge you for) into a container for Sudan for use the following April/May it was used on 26 sub 100 metre dives down to a maximum of 213 meters and after a 7 hour run time there was still an hour remaining on the rEvo top scrubber.


Should add that me had no issues.

Pardon??

Any links to information on the expedition, or is that to follow??

ta.

matt
20-06-2017, 03:57 PM
What was the water temperature at 213m and at 6m?

Matt.


Bit old this thread but hey I've been busy.

We took Insersurgical Dive Lime to Sudan for an Expedition. That means that we shipped it in September to Italy and it was then stuffed (yep that's the word that they use and charge you for) into a container for Sudan for use the following April/May it was used on 26 sub 100 metre dives down to a maximum of 213 meters and after a 7 hour run time there was still an hour remaining on the rEvo top scrubber.


Should add that me had no issues.

Capt Morgan
20-06-2017, 04:17 PM
What was the water temperature at 213m and at 6m?

Matt.

Hot and hotter, just an educated guess :)

Simon TW
21-06-2017, 06:08 AM
Pardon??

Any links to information on the expedition, or is that to follow??

ta.

It was 2015 James

http://www.tekdeep.com/2014/08/15/tekdeep-to-hunt-for-the-lost-italian-submarine-in-sudan/

Simon TW
21-06-2017, 06:11 AM
What was the water temperature at 213m and at 6m?

Matt.

It was spring so not as warm at 6 as would have been in the summer. Approximately 19 and 27 so not a cold water dive.

matt
21-06-2017, 08:49 AM
It was spring so not as warm at 6 as would have been in the summer. Approximately 19 and 27 so not a cold water dive.

I haven't pushed the Inspo scrubber in the 19c range, but I have in the 27c range and yes, you can get ~9h before the warning in that temperature. I have no experience at those depths - did you use a heliox?

Matt.

Mark Chase
22-06-2017, 07:46 AM
It does make me laugh that 10 years ago I was getting slated for running 6 hours on a scrubber but now we have temp sticks & scrubber moniters, its all fine and I am hearing 9+ hours being possible :)

I once told Paul (rEvo fame) that somone had done 10 hours on a Inspo single dive shallow sub 15m depths (cave) 20c and he suggested it was not possible but now it seems the new norm?

Its worth remembering that with any push past the standard 3 hour rule your reducing the margins of error. IMHO if your pushing past 6 hours, the margins are too close for comfort.

ATB

matt
22-06-2017, 10:08 AM
Yup, that's all true. And without the TempStick I would (and did) stick strictly to the 3h rules.

For sure you are pushing the margin for error, and I would not want to have mandatory deco at the 9 hour point, but for shallow holiday diving where a direct ascent is perfectly possible I do not see the risk as any higher than leaving the bottom with 30 bar.

And to be clear you should start any dive requiring deco with a fresh scrubber IMHO.

Matt.


It does make me laugh that 10 years ago I was getting slated for running 6 hours on a scrubber but now we have temp sticks & scrubber moniters, its all fine and I am hearing 9+ hours being possible :)

I once told Paul (rEvo fame) that somone had done 10 hours on a Inspo single dive shallow sub 15m depths (cave) 20c and he suggested it was not possible but now it seems the new norm?

Its worth remembering that with any push past the standard 3 hour rule your reducing the margins of error. IMHO if your pushing past 6 hours, the margins are too close for comfort.

ATB

graham_hk
22-06-2017, 03:33 PM
...

Hot Totty
22-06-2017, 07:01 PM
If you understand the test conditions giving 3h rating on inspo (and JJ and maybe others) you would know that 3h is very conservative and therefore some extrapolation to longer times is possible. The big question is how far can one extrapolate safely. I know what has worked in the past for my CCR for me but there is some risk to assuming it will be all ok in the future based on that.

It's an exponential curve, at some point it will bite you - when that is is anyone's guess, technology can help but if you've stepped outside manufacturer's guidelines.........................

matt
22-06-2017, 08:51 PM
What do you mean by stepping outside the manufacturers guidelines? How do you interpret the Temp Stick guidelines?

Matt.


It's an exponential curve, at some point it will bite you - when that is is anyone's guess, technology can help but if you've stepped outside manufacturer's guidelines.........................

Mark Chase
23-06-2017, 07:12 AM
What do you mean by stepping outside the manufacturers guidelines? How do you interpret the Temp Stick guidelines?

Matt.

Does the temp stick have guidelines which state you can dive to the temp stick limits/

I had assumed the Inspo was a 3 hour rated scrubber and if you used it past 3 hours on your head be it.

The temp stick is supposed to be there to monitor scrubber errors and breakthrough due to incorrect packing and accidental over use.

PS I am no concerned about people diveing to the temp stick my comments before were ironic and aimed at all those who said I was being reckless.

I chose a scrubber limit based on maths. I calculated I could get about 9 hours out on my scrubber so set a limit of 6

Aparently this is reckless but reliance on a bit of tec is not?? Go figure

Mark Chase
23-06-2017, 07:27 AM
If you understand the test conditions giving 3h rating on inspo (and JJ and maybe others) you would know that 3h is very conservative and therefore some extrapolation to longer times is possible. The big question is how far can one extrapolate safely. I know what has worked in the past for my CCR for me but there is some risk to assuming it will be all ok in the future based on that.


C02 = 85% VO2

V02 = 4% RMV

Scrubber calculations are done on a C02 production of 1.6lpm 40RMV at 40m in 4C water


A rough way of doing it would be if your RMV is 10 and the scrubber is rated at 3 hours @ 40RMV you should be able to get 12 hours


4% RMV 10 = 0.4

85% of 0.4 = 0.34

Test level C02 production was 1.6lpm

1.6 divided by 0.35 = 4.7

So in theory you can go to 4.7 X test result because scrubber performance is based on how much C02 it can absorb and this is related to the amount of C02 you put through it


Other issues influencing the result is time at depth and water temp. So if your diving in water warmer than 4c you have an increased margin of error. If your doing dives to 30m not 40m you have an increased margin of error


Personaly I did the calc on 15 SAC (my SAC is around 10) so I get 2.6 X test = 7.8hours and I rounded that down to 6 to give me a max planned duration with a margin of error.


Who needs a temp stick????

gobfish1
23-06-2017, 08:58 AM
My C02 production working off o2 used is about .6lpm so im good for noddy diving


RMV SAC lol thats bailout talk ,

matt
23-06-2017, 11:28 AM
Does the temp stick have guidelines which state you can dive to the temp stick limits/

There's no time guidelines if that's what you mean. The Temp Stick works by showing you the Sofnolime decay, and when you get to the last block you get a warning (3-5mbar PCO2):

https://s6.postimg.org/5f6srgltd/scrubber-1block.jpg

The second warning comes when the Sofnolime is exhausted (5-10mbar PCO2):

https://s6.postimg.org/53pcep5dd/scrubber-0block.jpg

I've never seen 1 block, my tests have only ever been to 2 blocks (9h in warm water). I didn't really trust it until I also got the CO2 sensor to test it against.


I had assumed the Inspo was a 3 hour rated scrubber and if you used it past 3 hours on your head be it.

Rated for 3h at CE condition. Can be used longer with Sofnolime 797 and the Temp Stick.


The temp stick is supposed to be there to monitor scrubber errors and breakthrough due to incorrect packing and accidental over use.

That's one of it's uses, but not the primary use.


PS I am no concerned about people diveing to the temp stick my comments before were ironic and aimed at all those who said I was being reckless.

I chose a scrubber limit based on maths. I calculated I could get about 9 hours out on my scrubber so set a limit of 6

Aparently this is reckless but reliance on a bit of tec is not?? Go figure

The only real difference with the maths approach and the bit-of-tech approach is that you don't see the other errors you can see with the Temp Stick (as you pointed out already). And it gives you some real idea what's going on, outside of remembering to set your timer.

If I gave you a used scrubber and a Temp Stick, about 30 mins into a dive you would know how much this scrubber had been used for - it helps stop mistakes.

YMMV.

Matt.

Alby R
23-06-2017, 12:13 PM
The temp stick is supposed to be there to monitor scrubber errors and breakthrough due to incorrect packing and accidental over use.


hi matt

i have moved onto a jj from my vision, and i must say i do miss the temp stick.

re this quote i was always under the impression that the temp stick monitored the temperature, not breakthroughs or incorrect packing, these would be for a co2 monitor surely

alby

matt
23-06-2017, 02:05 PM
The monitor is for temperature, but it is tested against actual CO2 breakthrough. The limits I posted are from "the list" by the factory. They are also the CE test conditions. For CE marking if you have a device it must be tested and must work.

I agree, though. I decided not to make any scubber endurance trials on myself and stuck to changing the scrubber daily for quite some time.

Then I bought the CO2 sensor and reasoned that if this measures the actual CO2 then I could calibrate (my mind) to understand what the fancy thermometer was telling me.

I've done many many trials in 27c or warmer water. This is where you get the big advantage, and also where you are most likely to find supply issues and high cost. I settled on 2-blocks remaining to give some extra comfort, same as Mark describes in his mathematical calculation.

I have done some limited trials in cold-water, but would not gas dive on a used scrubber as it is not worth any risk with decompression.

I've also done some storage tests of my own invention.

I find the information interesting and helpful; more so than only having the CE test data and some theoretical-math to follow.

Matt.


hi matt

i have moved onto a jj from my vision, and i must say i do miss the temp stick.

re this quote i was always under the impression that the temp stick monitored the temperature, not breakthroughs or incorrect packing, these would be for a co2 monitor surely

alby